TM 9-4120-357-14
TABLE 5-1.
TROUBLESHOOTING (Cont)
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
3.
INSUFFICIENT COOLING.
Step 1.
Check sight glass liquid indicator for bubbles. If bubbles exist check system for leaks.
Repair leaks, and recharge system.
Step 2.
Feel drier-strainer (dehydrator) to see whether it is cold to the touch, or is frosted or sweating. Cold dis-
charge indicates obstruction.
Discharge system over a period of 5-6 hours to prevent oil being blown out of system, then replace
drier-strainer.
Step 3.
Check inlet and discharge side of solenoid valves for temperature difference. Abnormally cold discharge
indicates a leakage or obstruction.
Step 4.
Check evaporator coil for over-all temperature. If part of coil is relatively warm, and evaporator refriger-
ant inlet is sweaty of frosty, expansion valve may be damaged or obstructed.
Discharge system over a period of 5-6 hours to prevent oil being blown out of the system, then re-
place expansion valve.
4.
Step 1.
Check sight-glass liquid indicator for bubbles indicating low charge of refrigerant. If bubbles are present,
check refrigeration system for leaks.
Discharge system over a period of 5-6 hours to prevent oil being blown out of system, then repair
leaks or replace leaking component.
Step 2.
If icing is present check
hot gas bypass pressure regulating valve setting (suction pressure).
CAUTION
Do not use steam, open flame, heat gun or any other high-
temperature heat source to thaw an iced evaporator coil.
Thaw an iced coil with a lamp bulb (75-watt maximum), hair dryer or electric fan, and adjust pressure
regulating valve.
5-5